My Mum is your age, so this breaks my heart.
You don't deserve to be emotionally abused and I am so happy you have a dog, I have two little ones myself, when I am down a bit, due to work load they just bring me back up, the love is so unconditional isn't it.
I just want to say, that whether he is your son or not, you need to live the rest of your life happy. So the AVO was suggested to you, I understand you didn't know the full effect of it, but it was in my opinion, suggested to you for a reason, so you can breathe, not be abused, enjoy your life, so please, please, get rid of that guilt.
This World can be carp can't it, drugs people thing eases loneliness, money issues, all sorts of things but it doesn't. He has to find his way.. It's not your responsibility anymore as he's stubborn and you need a break.
We have the children, we do everything we can, but when they mature, they will go their own way. Remember his youth and the good times and just remind yourself that as an Adult they will become who they want, and in that, if that does not fit how you live, you don't have to live it.
I commend you for wanting the peace you so much, so much deserve, so again please don't be upset about the AVO, you did what is best for you and the right thing for you.
I hope you have sisters ,brothers, nieces, people, best friends, call them, just for a chat, talk about life, things you love, you have a lot of love to give and need it in return.
I also hope you come back, and chat with us, strangely enough, people on this Forum very, much become family. And, I would love to be there for you as I know others here would too, even to simply talk to us daily about your day.